The invention relates to a printer comprising two printing stations, each having a printing head which can be mounted on a carriage guided displaceably parallel to a print backing means.
A printer of the type mentioned above is disclosed, for example, by EP B 0 195 949. It is used, for example, as a cash-register printer having a printing station each for voucher/journal and receipt. In the case of the known printer, in each case the entire printing system can be constructed as an interchangeable subassembly on a printing station which, in addition to the printing head, also comprises the print backing means, the transport and guiding means for the line feed and, if appropriate, also the ink carrier device. This provides the option of producing the printer in its basic form in very large numbers, it being possible for the equipment of the various printing stations to be defined individually in accordance with the wish of the customer at any time until immediately before delivery. Furthermore, the customer also has the option of himself changing individual printing stations from one printing process to another, without having to buy a completely new printer. However, changing from one printing process to another requires the replacement of the entire subassembly, as already mentioned above.
DE OS 2 232 590 further discloses a printer having a carriage which can be moved parallel to a print backing means and on which different printing heads can optionally be plugged.
EP A 0 623 471 describes an inkjet printer having a printing station in which in each case printing heads containing different printing colors are arranged on a carriage. The printing heads are used to print on one and the same recording medium.
EP A 0 359 580 discloses a printer having two printing stations, each of which has a carriage guided displaceably parallel to a print backing means. Provided on each carriage is a printing head holder which is fixed to the carriage and which, in turn, in each case contains six holders for six individual wire printing heads. The printing directions of the printing stations are oriented at right angles to one another.
The invention is based on the object of specifying a printer of the type mentioned at the beginning in which the two printing stations take up little space and can be changed over in a very simple way from one printing process to another.
For a printer which has a carriage with two printing-head holders fixed to the carriage and having holding means for the detachable holding of a printing head each, this object is achieved by the characterizing features of claim 1.
Arranging both printing-head holders on one and the same carriage permits a space-saving arrangement of the two printing stations in the printer. For the transition from one printing process to another within a printing station, it is merely necessary for the printing head itself to be replaced.
The respective printing-head holder is designed for a first type of printing head and can be connected to a printing-head adapter which, in turn, is designed to hold a printing head of a different type. In order to interchange the printing head, one therefore needs merely to replace the printing head of the first type by the adapter connected to the printing head of a different printing technology. In this case, the configuration of the printing-head holder and the replacement operation are particularly simple if the printing-head adapter can be connected to the printing-head holder by the holding means on the latter, that is to say if the adapter, at its end facing the printing-head holder, is configured in the same way as the printing head of the type intended for direct insertion into the printing-head holder.
Replacing the printing head is particularly simple if the holding means are designed as latching means, so that the replacement of the printing heads can be carried out without the aid of tools.
In a preferred embodiment of the printer according to the invention, the printing-head holder is in each case designed to hold an inkjet printing head, while the printing-head adapter is designed to hold a dot-matrix printing head. Depending on whether it is wished to print single sheets or, for example, carbonless sets for receipts, it is possible either for inkjet printing heads to be used on both printing stations or for an inkjet printing head to be used on one printing station and a dot-matrix printing head to be used on the other printing station.
For the simultaneous printing of vouchers and receipts, it is particularly advantageous if the printing-head holders are arranged on the carriage in such a way that the printing direction of the printing heads held in them are at right angles to each other.
Both printing stations are preferably activated by the same control device, it then being expedient for a distributor circuit to be arranged on the carriage, being connected to the control device and having a connection for each printing head. When the printing heads are replaced, it is therefore merely necessary for the respective printing head to be connected to the correct connection of the distributor circuit.
The connection between the control device and the distributor circuit is preferably a flat ribbon connector, in particular a flexible ribbon.